I dated a guy with HIV. We didn't know he had it when we met; we went out a few times, and had postponed sex till we both got tested. He was only 19, and had only started seeing guys the year before.
I stood by him as much as I could, and told him that that didn't change anything, since I really cared for and loved him. (We just had to use those really strong and thick female condoms that's virtually unbreakable, lol.) But his family insisted that he moved back home in the US to support his treatments and such, so he did...
Now he's doing fine, and is "undetectable" -- literally more safe and more risk free (having sex with him) than hooking up bareback with a sexually active stranger who's untested (according to the HIV centers here). And with PrEP which virtually prevents its spreading, I would have unprotected sex with him if we were still together... not saying I totally won't be afraid, but yeah.
My point is, if I really love someone, I would date him even if he were 'positive.' I'm grateful for that experience; it taught me a lot about things, including who I am or can be. (Yes, I was one of those who wouldn't have dated him if I knew he was positive prior to dating, but wouldn't have minded being his friend.) And with medicine's progress in that area, it's a far different situation now than before when it comes to risk and safety.
I feel bad for the judgments a lot of people get, and wish more and more people will be more educated. I agree that your friend should just let others know early on, but it's really up to him (...a must, before sex though, as someone mentioned.) If he tries to live healthy and strictly stick to its medical protocols, he will be undetectable soon enough and won't transmit anything at all. (That's what the doctors said, also there's no reason for hiv positive people now to not die of old age.)
He just has to find the right (educated, non-judging) person... esp. now that he's still on his way to 'recovery' or being undetectable.